1. Technical Field
The present invention generally relates to displaying of images.
2. Description of Related Art
Some display apparatuses are developed not only to be light, thin, compact and small, but also to display stereoscopic images. Generally, the principle of displaying three-dimensional (or “stereoscopic”) images is to display two different images to the left eye and the right eye of the viewer, respectively. As such, a stereoscopic image can be perceived by the human brain of the viewer through mixing these two images. Conventionally, there are two methods for displaying different images to the left eye and the right eye; one is the grating technique, the other is the polarization technique.
With respect to the grating technique, the light beams of different images will pass through different gratings and respectively enter the left eye and the eye of the viewer. Alternatively, the polarization technique utilizes the polarity of light. For instance, the light of one image only exhibits linear polarizing of a vertical direction and the light of the other image exhibits only linear polarizing of a horizontal direction. Meanwhile, the left eye and the right eye of the viewer can receive the corresponding images with the use of polarized lenses exhibiting appropriate polarizing directions so that the viewer can perceive a stereoscopic image.
FIG. 1 is a cross-sectional view showing a conventional display apparatus. As shown in FIG. 1, a display apparatus 1000 comprises a display module 1100 and a polarization controller 1200. The display module 1100 has a plurality of pixel regions 1120 arranged in an array. Each of the pixel regions 1120 has a first sub-pixel region 1122, a second sub-pixel region 1124 and a third sub-pixel region 1126. When the display module 1100 is driven, the first sub-pixel region 1122, the second sub-pixel region 1124 and the third sub-pixel region 1126 provide red light 1122a, green light 1124a and blue light 1126a, respectively. The red light 112a, the green light 1124a and the blue light 1126a also exhibit linear polarization.
When red light 1122a, green light 1124a and blue light 1126a pass through the polarization controller 1200, the polarizing directions of the red light 1122a, the green light 1124a and the blue light 1126a will deflect. After the polarizing directions of the red light 1122a, the green light 1124a and the blue light 1126a deflect, the horizontal components of the red light 1122a, the green light 1124a and the blue light 1126a enter the left eye of the viewer through the polarized glass having the horizontal polarizing direction and the vertical components of the red light 1122a, the green light 1124a and the blue light 1126a enter the right eye of the viewer through the polarized glass having the vertical polarizing direction. Based on the horizontal components of the red light 1122a, the green light 1124a and the blue light 1126a with the left-eye image information of the stereoscopic image and the vertical components of the red light 1122a, the green light 1124a and the blue light 1126a with the right-eye image information of the stereoscopic image, a stereoscopic image can be perceived by the viewer.
However, light beams with different wavelengths generate different phase retardations after passing through the polarization controller 1200. The conventional polarization controller 1200 is made of a single material of uniform thickness. If the design of the polarization controller 1200 is to lead the blue light 1126a generating π/2phase retardation, the phase retardation of the green light 1124a is smaller than π/2, and the phase retardation of the red light 1122a is smaller than that of green light 1124a. Hence, the components of the green light 1124a and the red light 1122a entering the left eye and the right eye through the polarized glasses, respectively, differ from ideal. That is, the stereoscopic image perceived by the viewer is incorrect.
In order to solve the problem mentioned above, another conventional technique is performed to estimate the difference in phase retardation of light beams with different wavelengths after the light beams pass through the polarization controller 1200 and to compensate for the difference in phase retardation in advance when driving the display module 1100. However, the aforementioned technique requires relatively complex and expensive circuitry to implement the data calculation.